The answer is D. He placed family members in charge of regions.
The land of Zhou was a vassal state of the Shang Dynasty. A powerful leader of the Zhou named Wen Wang began to plan to overthrow the Shang Dynasty. The Zhou Dynasty was divided up into the Western Zhou and Eastern Zhou periods. It extended its power over the eastern plain by granting authority to members of the royal family and in some cases to favored adherents, that established walled forts supported by garrison troops among the original habitants of the east.